For example, an inverter of large capacity for performing bidirectional conversion between direct current electric power and alternating current electric power is required in a hybrid automotive vehicle having both an internal combustion engine and an electric motor as a driving source, an automotive vehicle having an electric motor as a driving source, and the like. Therefore, electric power converters including this inverter have been variously developed.
An inverter circuit (i.e., an electric power converting circuit) is constructed by using a semiconductor module including an IGBT element, and the like, therein. However, since the inverter circuit has large capacity, as mentioned above, a large amount of heat is generated. Therefore, as shown in FIG. 6, the conventional electric power converter 9 is constructed by assembling a cooling device 91 for cooling the above semiconductor module 92.
More concretely, the semiconductor module 92 is arranged so as to face the cooling device 91. A power wiring section 93 for supplying an electric current of a bus bar, etc. to the semiconductor module 92 and stopping the supply of the electric current is arranged so as to face the semiconductor module 92. Further, the electric power converter 9 is constructed by arranging a control circuit substrate section 95 through a shield layer 94. The control circuit substrate section 95 controls the operation of the semiconductor module 92. However, it is indispensable that the above shield layer 94 is interposed and arranged to avoid the influence of noises from the above power wiring section 93. For example, the structure of such an electric power converter is shown in JP-A-H11-69774.
However, there are the following problems in the conventional electric power converter 9. Namely, it is indispensable in the above conventional electric power converter 9 that the above shield layer 94 is interposed and arranged to raise the operating performance of the control circuit substrate section 95. Therefore, the number of parts required is increased and it is difficult to reduce costs.
Further, the influence of noises from the power wiring section 93 to the control circuit substrate section 95 can be reduced by the above shield layer 94. However, a connecting line 955 for connecting the control circuit substrate section 95 and the semiconductor module 92 still penetrates portions of the shield layer 94 and the power wiring section 93. Therefore, it is difficult to remove the influence of the noises on the above control circuit substrate section 95.
Further, for example, in the electric automotive vehicle and the hybrid automotive vehicle, as shown in FIG. 25, the direct current of a battery 1500 is converted into an alternating current by an inverter device 1510, and an alternating current generator 1505 is operated. The inverter device 1510 includes plural semiconductor modules.
As is well known, each semiconductor module has an internal semiconductor element (switch element) 1511, a pair of electrodes on both sides of the semiconductor element 1511, and a signal terminal connected to an external control circuit. The semiconductor element 1511 is switched by a control signal inputted from the control circuit 1512 through the signal terminal, and an artificial alternating current is generated.
During operation of the semiconductor module, noises of high frequencies are generated in its electrically conductive portion and are emitted from direct current power lines 1514, 1515 and an alternating current power line 1516. To prevent this, high frequency capacitors 1521, 1522 and 1523 are connected between the direct current power lines 1514, 1515 and the ground and between the alternating current power line 1516 and the ground through a lead wire 1526 so that a noise component is bypassed.
On the other hand, a conventional self-excited type rectifying circuit (see JP-A-07-308070) shown in FIG. 26 includes self-excited type rectifying circuit portions 1532 and 1535 for converting an alternating current supplied from a commercial electric power source 1530 into a predetermined and desirable direct current voltage. Noises generated by a switching operation of a rectifying element 1536 constituting the rectifying circuit portion 1535 are introduced into the commercial electric power source 1530 and have a bad influence on the commercial electric power source.
To prevent this, a noise restraining circuit 1540 is arranged between the self-excited type rectifying circuit portions 1532 and 1535. The noise restraining circuit 1540 includes a noise restraining reactor 1542 arranged in each phase line 1541, a capacitor 1544 arranged between the respective phase lines 1541, and a capacitor 1546 arranged between one phase line and the ground. The noise restraining reactor 1542 and the capacitor 1544 restrain the emission of a normal-mode noise, and the capacitor 1546 restrains the emission of a common-mode noise.
The above inverter device 1510 of the electric automotive vehicle, etc. has the following problems. The lead wire 1526 for connecting the high frequency capacitors 1521 to 1523 to the electric power lines 1514 to 1516 has a large resistance component and a large inductance component. It is necessary to increase the capacities of the high frequency capacitors 1521 to 1523 to obtain a sufficient noise restraining effect by reducing the impedance of a bypass path. Thus, a high frequency electric current transmitted via the high frequency capacitors 1521 to 1523 becomes a leaked electric current, and this leaked electric current creates an error in the operation of the inverter device 1510.
Further, since the semiconductor module is a noise generating source and the high frequency capacitors 1521 to 1523 for bypassing noises are separated from each other, the noises are inevitably emitted to a certain extent from the electric power lines 1514 to 1516 between the semiconductor module and the high frequency capacitors 1521 to 1523.
On the other hand, with respect to the above self-excited type rectifying circuit, only the arrangement of the reactor 1542 with respect to each phase line 1541, and the capacitor 1544 between the respective phase lines 1541, etc. are shown. No concrete mounting method of the capacitors 1544, 1546 is shown. In any case, if the capacitors 1544, 1546 are poorly arranged, cost and a space are correspondingly increased. Further, a resistance component, etc. exists in the lead wire for connecting the capacitors 1544, 1546 to the phase line 1541. Further, the capacitors 1544, 1546 are separated from the rectifying circuit portion 1535 so that noises are easily emitted from the phase line 1541 between the capacitors 1544, 1546 and the rectifying circuit portion 1535.
The present invention is made in consideration of such conventional problems, and a first object of the present invention is to provide an electric power converter capable of reducing the number of parts and restraining the influence of noises from the power wiring section. A second object of the present invention is to provide the mounting structure of a semiconductor device capable of effectively restraining the emission of noises generated in the semiconductor element without externally attaching a special bypass capacitor.